青藏高原可液化土层钻孔桩施工关键技术研究

针对青藏高原察格高速公路穿越地下水较丰富沼泽区的特点，选择某简支梁桥12根直径为2．2m桩径约为20m的钻孔灌注桩施工过程为分析对象，对其关键技术逐一分析，并得到如下结果：钻孔桩穿越可液化土层时钻孔速度需控制在0．7m／h左右，不同地质和不同层位可适当调整；桩基混凝土浇筑速度需控制在10m／h左右，混凝土充盈系数平均值为1．069，远低于定额规定；泥浆与混凝土的配制方案经检测较适合该地区水下混凝土施工。同时，就钢筋笼上浮和井口钢筋笼焊接控制技术提出建议。

Research on Critical Techniques for Construction of Drilled Piles on Liquefiable Soil in Qinghai-Tibet Plateau

In allusion to the feature of Cha＇ erhan-Ge＇ ermu Expressway in Qinghai-Tibet Plateau crossing swamp area with rich underground water, this paper selects construction of 12 drilled grouting piles at diameter of approximate 2. 2 m and pile diameter of about 20 m of some simply supported beam bridge to analyze their critical techniques one after another and obtains the following results： as drilled piles cross liquefiable soil, the drilling speed should be controlled at approximate 0. 7 m/h, and can be properly adjusted for different geological conditions and positions; the pouring speed of pile foundation concrete should be controlled at about 10 m/h, and the average of filling coefficients of concrete is 1. 069, much lower than the specified quota; the preparation plan of mortal and concrete after detection is applicable to underwater concrete construction in this region. In the meantime the paper proposes recommendations for steel-reinforced cage up-floating and wellhead steel-reinforced cage welding control techniques.